Increased energy consumption and the depletion of petroleum reserves have pushed up oil prices globally. Diminishing the petroleum reserve is another global risk factor. ProducingBiodiesel vegetable oils and animal fat by transesterification can be a considerable energy alternative. In this study, biodiesel is produced from waste cooking oil by transesterification method with methanol in the presence of HCl as a catalyst. Biodiesel production begins with mixing raw the collected used cooking oil into one pool. The mixture is then settled for 8 hours at room temperature before initiating the transesterification process 90^oC by mixing HCl (1% of oil weight) with methanol, while the methanol: oil ratio is 1:4. The process lasts for 9 h under a condenser. Biodiesel purification is carried out by washing the product twice with hot water (temperature 70°C) to remove excess reactants and byproducts such as alcohol, catalysts, soap and glycerine, and fatty acid methyl ester (FAME). The resulting diesel density of 3.72 kg/m (at 15ºC), a kinematic viscosity of 8.93 mm/sec., at 40ºC, calorific value was 41299 kj/kg, Total acid number of 0.111 was for waste cooking oil, Cetane number of 48.95, acid value (AV) was 1.135 mg/koh was and Ester value (EV) was 178.42 mg/koh. The Saponification value (SV) was 179.56 mg/koh, pH was 5.7, and Glycerol Weight was 97.53 (Gw).